"should", sure, but vendors (I mostly run into this w/Chrome but other vendors do it too) happily just ignore the spec because it's inconvenient and sometimes e

"should", sure, but vendors (I mostly run into this w/Chrome but other vendors do it too) happily just ignore the spec because it's inconvenient and sometimes explicitly have no plans to ever align with it. I recently ran into a case where Chrome was intentionally moving away from the spec without making any effort to update the spec, because being correct was... annoying. Not impossible or bad for users, just annoying. At the time the behavior worked right in Firefox and Edge but now that Chrome is going to ignore the spec I suspect the other vendors might too. (For reference, it was an issue related to the lifetime of javascript objects for frames that have been unloaded or navigated) This sort of thing will never appear in a compatibility matrix. You find out when it breaks your code.